Things I Make And Cut On At Work

[Wreck™Wreck]

Nasty turning job on Wed., 10 1/2" Dia. plastic bead impeller for a large scale injection molder, 304 stainless weldment.

Turning the bearing journals at 350 rpm's turned it into an excellent fan, facing the vane ends was a testament to the Sandvik SS interrupted cut inserts which worked flawlessly considering the conditions, I faced it at 90 Rpm's and it still sounded like a train wreck.

Safety First, I stood 5 feet away when it was running.


Some .001" shim material was required in the center to reduce the run out, this can be a maddening process at best.

 

[Tony Wells]

I would have recut that center. Obviously the shaft is bent or distorted from the welding. Next guy would thank you.

 

[Ulma Doctor]

Nasty turning job on Wed., 10 1/2" Dia. plastic bead impeller for a large scale injection molder, 304 stainless weldment.
Turning the bearing journals at 350 rpm's turned it into an excellent fan, facing the vane ends was a testament to the Sandvik SS interrupted cut inserts which worked flawlessly considering the conditions, I faced it at 90 Rpm's and it still sounded like a train wreck.
Safety First, I stood 5 feet away when it was running.
Some .001" shim material was required in the center to reduce the run out, this can be a maddening process at best.

Hi Wreck!
i don't envy your task above!
everytime i gotta work 304, i say the old mantra- 304 is a ....(explative)

i'm curious how you came up with the shim placement and thickness?
at the risk of sounding dense, i think i am i overthinking this,
was it just indicateing poorly and you found the low?
or what it the PITA i thought it may be?
i have not had the pleasure to try, or had the real need, to work from a poor center like that.
it is nice to know that out of the box doing, accomplishes things that thinking , never will
nice job, good save Wreck!

 

[Wreck™Wreck]

I would have recut that center. Obviously the shaft is bent or distorted from the welding. Next guy would thank you.

Not bent nor distorted (machine after welding) simply the normal difference between machines, it had a TIR of .003" as is, which I find excellent on a used part 20" long, I do not pursue the .0001 hobbyist penchant for accuracy only what is required for the job at hand.

As far a drilling a new center this would require setting up a steady rest to do so, also the next person will put this part in a different machine. For all I know the .003" was in the live center that I used.

 

[Tony Wells]

I know what it would have required, Wreck. And re-drilling is not it. Yes it would require a steady rest, but that's no biggie. I never suggested that a tenth runout would be needed. Remember, I'm not a hobbyist. But obviously you thought the 0.003 was unacceptable. It would have taken about 2 minutes to check the center. Was runout spec'd on the print? Are you going to discard that center if it proves to consistently run 0.003 out? It seems either that center or the one previously used to turn the part, at least where you were indicating, is at fault.

Just curious.

 

[Wreck™Wreck]

Hi Wreck!
i don't envy your task above!
everytime i gotta work 304, i say the old mantra- 304 is a ....(explative)

i'm curious how you came up with the shim placement and thickness?
at the risk of sounding dense, i think i am i overthinking this,
was it just indicateing poorly and you found the low?
or what it the PITA i thought it may be?
i have not had the pleasure to try, or had the real need, to work from a poor center like that.
it is nice to know that out of the box doing, accomplishes things that thinking , never will
nice job, good save Wreck!

Common practice in a job shop, put the shim on the high spot, common paper works well for small parts, this may take considerable time to get right however. This part only ran out .003" total which would be more then adequate for what it does, I tucked a piece of .001 steel shim into the center and it then ran out .001 the first time, pure luck, if it had not corrected after the first try I would have just turned the part anyway.

 

[Wreck™Wreck]

I know what it would have required, Wreck. And re-drilling is not it. Yes it would require a steady rest, but that's no biggie. I never suggested that a tenth runout would be needed. Remember, I'm not a hobbyist. But obviously you thought the 0.003 was unacceptable. It would have taken about 2 minutes to check the center. Was runout spec'd on the print? Are you going to discard that center if it proves to consistently run 0.003 out? It seems either that center or the one previously used to turn the part, at least where you were indicating, is at fault.

Just curious.

You do not often use a 500 LB steady do you? I also know how to indicate a live center however buying a new 7MT live center is not something that makes my employer smile.

 

[Tony Wells]

Not in my shop, but I have more times than I can count, and larger ones as well. If your shop is properly tooled up for that kind of work, there's nothing to it.
I have yet to meet a business owner who smiles at the thought of spending money, but I have seen one literally bounce a handful of mics out the door because they needed to be replaced and no one said anything. He wasn't smiling then either. Spending money when it keeps from making scrap is an accepted business practice, smile or not. That smile is immaterial.

 

[Wreck™Wreck]

Hi Wreck!
i don't envy your task above!
everytime i gotta work 304, i say the old mantra- 304 is a ....(explative)

i'm curious how you came up with the shim placement and thickness?
at the risk of sounding dense, i think i am i overthinking this,
was it just indicateing poorly and you found the low?
or what it the PITA i thought it may be?
i have not had the pleasure to try, or had the real need, to work from a poor center like that.
it is nice to know that out of the box doing, accomplishes things that thinking , never will
nice job, good save Wreck!

303 and 304 are excellent materials for turning, I have never had a poor finish in 304 until the tool fails, this might be after hundreds of parts, 17-4 is a bit harder on tooling,

 

[Wreck™Wreck]

Not in my shop, but I have more times than I can count, and larger ones as well. If your shop is properly tooled up for that kind of work, there's nothing to it.
I have yet to meet a business owner who smiles at the thought of spending money, but I have seen one literally bounce a handful of mics out the door because they needed to be replaced and no one said anything. He wasn't smiling then either. Spending money when it keeps from making scrap is an accepted business practice, smile or not. That smile is immaterial.

We are on the same page here, try and give a bit of guidance to people that request it, that is one of the reasons that I like this forum, I work in a shop with 7 other old guy machinists, all of which know everything.